America's new ambassador to japan involved in a serious despite. Caroline kennedy delivers a stern warning after a defiant move by china. Jim avila has the story. Reporter: Caroline kennedy greeted lie american royalty. Presenting her credentials to the emperor, daughter of a slain president. Missing from the resume, diplomatic experience but that did not stop her today, just two weeks on the job from delivering a blunt warning that china's sudden and unilateral demand that planes must check in before flying near these remote islands is dangerous. It may be symbolic but today china deployed its first aircraft to the region. A sign that despite ambassador kennedy's stern statement, china is not backing down from its demand for advanced notice from any plane flying over these uninhabited I understand. Her statements have made her an even bigger hero in japan. I'm proud to carry forward my father's legacy. Reporter: Serenaded today on her 56th birthday. &#9834; &#9834; Reporter: She has read to children and visited the tsunami zone, her appointment said to be an ego boost for japan. Japan is not as central as it used to be and now they get a kennedy and caroline kennedy at that. Reporter: Now her first crises suddenly propelling a famous but rookie diplomat into the big leagues. New trouble tonight in the

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